1. Field of the Invention
The present invention is in the field of refrigeration generally, and in a more particular sense has reference to refrigerated display cases used in food markets. In a still more specific sense, the invention relates to cases of the air curtain type, in which air is introduced from the surrounding ambient atmosphere to flow through the evaporator coils of a case during defrost cycles. Although the invention is illustrated with specific reference to a "reach-in" case in which there is a door closing the customer access opening, it is applicable as well to upright, open front cases in which the customer access is continuously open.
2. Description of the Prior Art
In display cases of the air-defrosted type, it is common to utilize dampers for the purpose of bringing the air passages of the case into or out of communication with the ambient atmosphere. It has been proposed in many instances to provide a separate operating motor and linkage for each damper, with the several motors being part of a common electrical circuit for the purpose of effecting joint actuation of the dampers between their open and closed positions. This may result in considerable expense, both with respect to the original cost and maintenance of the several electric motors, and also in light of the extensive electrical wiring and connections needed to link all of the motors for joint operation. This expense can be quite high in many instances. For example, in many food markets an entire, elongated array or bank of cases might be installed, in end-to-end relationship, in which each case or section of a case must of necessity include an entire series of inflow dampers, and another series of exhaust dampers.
Problems arise, further, when dampers are in relatively inaccessible locations, since they are often prone to malfunction, and must of course in any event receive periodic maintenance to assure their retention in good working order.
So far as is known, the prior art has not offered as yet, solutions to the indicated problems, which solutions will result in simultaneous operation of an entire row of paired inflow and exhaust dampers, utilizing the fewest possible number of electrical motors, a simplified electrical circuit, and interconnections of a mechanically simple nature that will reduce to a minimum the time and expense required for maintenance and repair of the damper system.
The present invention seeks to overcome these deficiencies noted in the prior art, and aims to do so while still permitting all the dampers to be mounted in a fully accessible position for the purpose of facilitating inspection and normal maintenance.